A Y molecular sieve and its preparation method and application

Abstract

The present invention discloses a modified Y-type molecular sieve, based on the total amount of the modified Y-type molecular sieve, the Y-type molecular sieve contains 2.0-6.0wt% of Na2O by mass; the ratio of the pyridine infrared acid content to the butylpyridine infrared acid content of the Y-type molecular sieve is 5-60; the pyridine infrared acid content is 0.05-0.6mmol / g, and the preparation method of the modified Y-type molecular sieve comprises the following steps: (1) pre-treating the NaY molecular sieve to obtain a de-sodiumated and de-aluminized Y-type molecular sieve; (2) treating the pre-treated Y molecular sieve obtained in step (1) with a NaNO3 aqueous solution; (3) adding the Y molecular sieve treated with the NaNO3 aqueous solution in step (2) to a naphthalenesulfonate aqueous solution for immersion treatment; (4) performing an ammonium salt ion exchange reaction on the treated molecular sieve in step (3), and then drying and roasting to obtain the modified Y molecular sieve of the present invention. The acidic center of the molecular sieve of the present invention is concentrated in the small pores of the molecular sieve, which can effectively improve the secondary cracking efficiency of the hydrocracking reaction.

Description

Technical Field

[0001] The present invention relates to a Y molecular sieve and a preparation method and application thereof, and in particular to a modified Y molecular sieve and a preparation method and application thereof. Background Art

[0002] Hydrocracking technology has the characteristics of strong raw material adaptability, great flexibility of product solutions, high selectivity of target products, good product quality, and high added value. It can directly convert various heavy and inferior raw materials into clean fuels and high-quality chemical raw materials. It has become one of the most important heavy oil deep processing technologies in modern oil refining and petrochemical industries, and has been increasingly widely used at home and abroad. Although the processing capacity of my country's existing hydrocracking units has exceeded 50.0Mt / a, the quality of domestic crude oil has deteriorated year by year, the import volume of high-sulfur crude oil has increased significantly, and environmental protection requirements for the refining process itself and the quality of petroleum products have become increasingly stringent, and the market demand for clean fuels and chemical raw materials has continued to increase. Therefore, hydrocracking technology will be more widely used, and at the same time, higher requirements will be placed on hydrocracking technology itself.

[0003] The core of hydrocracking technology is hydrocracking catalyst, which is a dual-function catalyst with cracking and hydrogenation activity. The cracking function is provided by acidic carrier materials such as molecular sieves, and the hydrogenation function is provided by active metals of Group VI and Group VIII in the periodic table loaded on the catalyst. Different reaction requirements are met by adjusting the dual-function positions of cracking and hydrogenation. As the cracking component of the hydrocracking catalyst, the performance of molecular sieve plays a decisive role in the reaction performance of the catalyst. At present, the most important type of molecular sieve used in hydrocracking catalysts is Y molecular sieve. The number and distribution of acidic centers of Y molecular sieve directly determine the reaction characteristics of the molecular sieve, especially the size of the pores where the acidic centers of Y molecular sieve are located directly determines the cracking reaction selectivity of the molecular sieve for a certain type of reactants and reaction products. Therefore, the allocation of the distribution of acidic centers is an important direction of the Y molecular sieve modification process. Generally, the modification technology of Y-type molecular sieve includes hydrothermal modification, chemical dealumination modification by inorganic acid, organic acid, salt and complexing agent, and modification methods combining hydrothermal and chemical dealumination. For example, patent CN96119840.0 adopts hydrothermal desulfurization combined with buffer solution treatment to modify Y molecular sieve; however, the modified Y-type molecular sieve obtained by the current modification method has acid centers distributed in different pores of the molecular sieve (micropores and secondary pores).

[0004] Patent CN96119840.0 uses hydrothermal desulfurization combined with buffer solution treatment to modify Y molecular sieve; Chinese patent CN96120016.2 discloses a high silicon crystallinity Y type molecular sieve and its preparation method, using NH4NaY as the reaction raw material, first using ammonium hexafluorosilicate to dealuminate and supplement silicon, then hydrothermal treatment, and finally treating with aluminum salt solution, the obtained Y molecular sieve maintains a high crystallinity while deeply dealuminating; U.S. Patent US4036739 discloses a hydrocracking method, which discloses a modification method of Y type molecular sieve, at a temperature of 315~899℃, and contacting with at least 0.5psi water vapor for a period of time. However, these modification processes all have the problem that the acid centers of the modified Y type molecular sieve are distributed in the molecular sieve pores of different sizes, and the molecular sieve acid sites have a large dispersion. Summary of the invention

[0005] In view of the shortcomings of the prior art, a first aspect of the present invention provides a modified Y-type molecular sieve.

[0006] A modified Y-type molecular sieve, based on the total amount of the modified Y-type molecular sieve, the Y-type molecular sieve contains 2.0-6.0wt% of Na2O by mass; the ratio of the pyridine infrared acid content to the butylpyridine infrared acid content of the Y-type molecular sieve is 5-60; the pyridine infrared acid content is 0.05-0.6mmol / g.

[0007] Preferably, the modified Y-type molecular sieve has a specific surface area of ​​600-900m 2 / g; pore volume 0.30~0.60ml / g; relative crystallinity 60%~140%, unit cell parameter 2.430~2.450; silicon-aluminum molar ratio (5~50): 1.

[0008] The second aspect of the present invention provides a method for preparing the modified Y-type molecular sieve of the present invention, which comprises the following steps:

[0009] (1) Pretreating the NaY molecular sieve to obtain a de-sodiumated and de-aluminized Y-type molecular sieve;

[0010] (2) treating the pretreated Y molecular sieve obtained in step (1) with an aqueous solution of NaNO3;

[0011] (3) adding the Y molecular sieve treated with the NaNO3 aqueous solution in step (2) to a naphthalenesulfonate aqueous solution for immersion treatment;

[0012] (4) The molecular sieve treated in step (3) is subjected to an ion exchange reaction with ammonium salt, and then dried and calcined to obtain the modified Y molecular sieve of the present invention.

[0013] Preferably, the pretreatment process in step (1) comprises: one or a combination of ammonium ion exchange, hydrothermal dealumination, aluminum salt dealumination, fluorosilicate dealumination and acid dealumination.

[0014] Preferably, the pretreatment process in step (1) includes:

[0015] (a) subjecting the NaY molecular sieve to an ammonium ion exchange reaction with an ammonium salt aqueous solution to obtain a sodium-free Y-type molecular sieve;

[0016] (b) subjecting the desodiumated Y-type molecular sieve to hydrothermal dealumination to obtain a hydrothermal dealumination product;

[0017] (c) subjecting the hydrothermal dealumination product to chemical dealumination to obtain the desodium-dealuminized Y-type molecular sieve, wherein the chemical dealumination is aluminum salt dealumination, fluorosilicate dealumination or acid dealumination.

[0018] Through the above technical scheme, the present invention provides a modified Y-type molecular sieve with acidic centers concentrated in micropores. The acidic centers in the mesoporous channels (secondary pores) of the modified Y-type molecular sieve are basically occupied by Na ions, leaving only the acidic centers in the micropore channels. By using alkaline organic substances of different molecular sizes such as pyridine and n-butylpyridine to measure the infrared acid content on the modified Y-type molecular sieve, the ratio of the infrared acid amount of pyridine to the infrared acid amount of butylpyridine can reflect the distribution of the acidic centers in the micropores and secondary channels.

[0019] The method of the present invention first performs Na ion exchange on the acidic center of the modified Y molecular sieve, then selects naphthalenesulfonate with a larger molecular size for adsorption treatment, and the naphthalenesulfonate anion is selectively adsorbed on the sodium ion with good accessibility distributed in the macropores, and then the molecular sieve adsorbed with the naphthalenesulfonate anion is subjected to ammonium exchange to remove the sodium ion that is not protected by the naphthalenesulfonate anion and exposed by the molecular sieve pores, and finally after roasting, the adsorbed ammonium ions and sulfonate ions are removed, so that the acidic sites distributed in the molecular sieve pores are exposed. The acidic center sites of the molecular sieve of the present invention are concentratedly distributed in the molecular sieve pores, which can effectively improve the secondary cracking efficiency of the hydrocracking reaction.

[0020] In the two-stage hydrocracking process for producing naphtha, the molecular sieve of the present invention is used as an acidic component to prepare a hydrocracking catalyst and as a second-stage cracking catalyst to process the intermediate distillate oil generated by the first-stage reaction, which can increase the naphtha yield, especially improve the light naphtha reaction selectivity, and has good application prospects. DETAILED DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] The first aspect of the present invention provides a modified Y-type molecular sieve, characterized in that, based on the total amount of the modified Y-type molecular sieve, preferably, the modified Y-type molecular sieve contains a Na2O mass content of 2.2~5.0wt%, more preferably 2.5~4.0wt%; preferably, the ratio of the pyridine infrared acid content to the n-butylpyridine infrared acid content of the Y-type molecular sieve is 10~40, more preferably 15~30; preferably, the pyridine infrared acid content of the modified Y-type molecular sieve is 0.08~0.5mmol / g, more preferably 0.1~0.4mmol / g.

[0023] Preferably, the modified Y-type molecular sieve has a specific surface area of ​​620-850 m 2 / g, more preferably 650~800 m 2 / g; preferably, the pore volume of the modified Y-type molecular sieve is 0.32~0.55ml / g, more preferably 0.35~0.50ml / g;

[0024] Preferably, the modified Y-type molecular sieve has a relative crystallinity of 70% to 130%, more preferably 80 to 120%; a unit cell parameter of 2.435 to 2.450, preferably 2.436 to 2.445;

[0025] Preferably, the modified Y-type molecular sieve has a silicon-aluminum molar ratio of (6-30):1, more preferably (8-15):1.

[0026] The modified Y-type molecular sieve provided by the present invention has acidic centers mainly distributed in micropores, while a small amount or even no acidic centers are distributed in mesopores, which can significantly improve the secondary cracking efficiency in the hydrocracking reaction process.

[0027] The characteristics of the distribution of acidic centers in the above-mentioned pores of the modified Y-type molecular sieve provided by the present invention can be reflected by the results of acidity measurements of the modified Y-type molecular sieve using pyridine and n-butylpyridine as two probe molecules. The molecular diameter of n-butylpyridine is about 0.8nm, and it can only enter the macropores of the modified Y-type molecular sieve provided by the present invention, reflecting the total amount of acidic centers in the macropores. The molecular diameter of pyridine is about 0.6nm, and it can enter the micropores and macropores of the modified Y-type molecular sieve, reflecting the total amount of acidic centers in all pores of the modified Y-type molecular sieve. The specific testing process can be: by pyridine and n-butylpyridine adsorption infrared spectroscopy, using the Nicolet 6700 Fourier transform infrared spectrometer of the American NICOLET company,

[0028] Take 20 mg of finely ground sample (particle size less than 200 mesh) and press it into a thin sheet with a diameter of 20 mm, and place it on the sample holder of the absorption cell; take 200 mg of sample (sheet) and place it in the hanging cup at the lower end of the quartz spring (record the spring length before adding the sample, x 1, mm), connect the absorption cell and the adsorption tube, and start to evacuate and purify, with the vacuum degree reaching 4×10 -2 Pa, the temperature was raised to 500 °C and maintained for 1 h to remove the surface adsorbent of the sample (at this time, it was recorded as the spring length after sample purification, x 2, mm). Then the temperature was lowered to room temperature, pyridine (or n-butylpyridine) was adsorbed to saturation, and then the temperature was raised to 160°C, balanced for 1 hour, and the physically adsorbed pyridine was desorbed (at this time, the spring length after pyridine adsorption was recorded as x 3, mm), and the total acid content was calculated using the pyridine (or n-butylpyridine) weight adsorption method.

[0029] The present invention adjusts the concentrated distribution of the acidic center in the micropores of the Y-type molecular sieve, thereby achieving control of the reaction of hydrocarbon oil molecules on the molecular sieve. The distribution of the acidic center is reflected by measuring the total amount of infrared acidity of pyridine and n-butylpyridine. For a conventional Y-type molecular sieve that has not been adjusted for acidic center in the pores, the ratio of the total infrared acidity of pyridine to the total infrared acidity of n-butylpyridine will generally be between 1.2 and 2.0. This can distinguish whether the acidic center in the mesopore of the Y-type molecular sieve is controlled.

[0030] When the total amount of acid measured using pyridine and n-butylpyridine for the modified Y-type molecular sieve is much larger than the conventional ratio, that is, when the ratio of the total infrared acid amount of pyridine of the modified Y-type molecular sieve to the total infrared acid amount of n-butylpyridine of the modified Y-type molecular sieve is 5-60 as defined above, it means that the acid centers contained in the modified Y-type molecular sieve are mainly concentrated in the micropores.

[0031] The second aspect of the present invention provides a method for preparing the modified Y-type molecular sieve of the present invention, comprising the following steps:

[0032] (1) Pretreating the NaY molecular sieve to obtain a de-sodiumated and de-aluminized Y-type molecular sieve;

[0033] (2) treating the pretreated Y molecular sieve obtained in step (1) with an aqueous solution of NaNO3;

[0034] (3) adding the Y molecular sieve treated with the NaNO3 aqueous solution in step (2) to a naphthalenesulfonate aqueous solution for immersion treatment;

[0035] (4) The molecular sieve treated in step (3) is subjected to an ion exchange reaction with ammonium salt, and then dried and calcined to obtain the modified Y molecular sieve of the present invention.

[0036] Preferably, the pretreatment process in step (1) comprises: one or a combination of ammonium ion exchange, hydrothermal dealumination, aluminum salt dealumination, fluorosilicate dealumination and acid dealumination.

[0037] Preferably, the pretreatment process in step (1) includes: one or more combinations of ammonium ion exchange, hydrothermal dealumination, aluminum salt dealumination, fluorosilicate dealumination and acid dealumination. In the present invention, the pretreatment of the NaY molecular sieve can be one or more steps of ammonium ion exchange, hydrothermal dealumination, aluminum salt dealumination, fluorosilicate dealumination and acid dealumination. The order of the steps is not limited, as long as the desodiumated dealumination Y-type molecular sieve can be provided. For example, the Na2O content of the desodiumated dealumination Y-type molecular sieve is less than 3% by weight, and the SiO2 / Al2O3 molar ratio is (5-50): 1, and the unit cell constant is 2.430-2.450. Generally, the NaY molecular sieve is first desodiumated by ammonium ion exchange, and then the desodiumated product is dealumination. One or more combinations of hydrothermal dealumination, aluminum salt dealumination, fluorosilicate dealumination and acid dealumination can be selected.

[0038] In a preferred embodiment of the present invention, the pretreatment process in step (1) comprises:

[0039] (a) subjecting the NaY molecular sieve to an ammonium ion exchange reaction with an ammonium salt aqueous solution to obtain a sodium-free Y-type molecular sieve;

[0040] (b) subjecting the desodiumated Y-type molecular sieve to hydrothermal dealumination to obtain a hydrothermal dealumination product;

[0041] (c) chemically dealuminating the hydrothermal dealumination product to obtain the de-sodium-dealuminized Y-type molecular sieve,

[0042] Wherein, the chemical dealumination is aluminum salt dealumination, fluorosilicate dealumination or acid dealumination.

[0043] According to the present invention, step (a) is used to remove Na ions in the NaY molecular sieve so that the subsequent dealumination process can proceed smoothly. Preferably, the process of the ammonium salt ion exchange reaction in step (a) is: exchanging the NaY molecular sieve with an ammonium salt aqueous solution at 60-120° C., preferably 60-90° C., for 1-3 hours, the number of exchanges is 1-4 times, to obtain the desodiumized Y-type molecular sieve.

[0044] Preferably, the Na2O content of the sodium-deionized Y-type molecular sieve is less than 3wt'%.

[0045] Preferably, the SiO2 / Al2O3 molar ratio of the NaY molecular sieve is (3-6):1, and the Na2O content is 6-12 wt%.

[0046] Preferably, the ammonium salt is selected from one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium acetate and ammonium oxalate, and the molar concentration of the ammonium salt aqueous solution is 0.3-6 mol / L, preferably 1-3 mol / L.

[0047] According to the present invention, step (b) is used to dealuminate the desodiumized Y-type molecular sieve to form macropores. Preferably, the hydrothermal dealuminate process in step (b) is: contacting the desodiumized Y-type molecular sieve with water vapor at a temperature of 520-700°C and a pressure of 0.01-0.5 MPa for 1-6 hours.

[0048] Preferably, the number of hydrothermal dealumination is 1-3 times.

[0049] According to the present invention, step (c) is used for chemical dealumination of the molecular sieve to form macropores. Preferably, the process of chemical dealumination in step (c) is: isothermally reacting the hydrothermal dealumination product with an aluminum salt solution, an ammonium fluorosilicate solution or a nitric acid solution at a temperature of 50-120° C. for 0.5-3 h.

[0050] Preferably, the aluminum salt solution is an aqueous solution of at least one of aluminum chloride, aluminum sulfate and aluminum nitrate.

[0051] Preferably, the molar concentration of the aluminum salt solution, ammonium fluorosilicate solution or nitric acid solution is 0.05-2 mol / L. When the product of the hydrothermal dealumination is subjected to the isothermal reaction with the aluminum salt solution, the aluminum salt dealumination is obtained. When the product of the hydrothermal dealumination is subjected to the isothermal reaction with the ammonium fluorosilicate solution, the fluorosilicate dealumination is obtained. When the product of the hydrothermal dealumination is subjected to the isothermal reaction with the nitric acid solution, the acid dealumination is obtained.

[0052] Preferably, the Na(NO3) aqueous solution treatment process in step (2) is to add the Y molecular sieve treated with aluminum salt in step (3) into a Na(NO3) aqueous solution with a concentration of 0.1-3.0 wt%, and heat to 40-80°C for constant temperature reaction for 1-4 hours;

[0053] Preferably, the naphthalenesulfonate used in the naphthalenesulfonate treatment process of step (3) can be an alkali metal salt such as sodium naphthalenesulfonate, potassium naphthalenesulfonate, etc., and the naphthalenesulfonate in the solution is 0.2-1 mol / L in terms of K or Na ion concentration, and the treatment conditions are stirring treatment at room temperature and the treatment time is 2-6 h.

[0054] Preferably, the ammonium salt ion exchange reaction step in step (4) is to exchange the molecular sieve obtained in step (3) with an ammonium salt aqueous solution at 60-120° C., preferably 60-90° C., for 1-3 hours, and the number of exchanges is 1-4 times. Preferably, the ammonium salt in step (4) is selected from one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium acetate and ammonium oxalate, and the molar concentration of the ammonium salt aqueous solution is 0.3-6 mol / L, preferably 1-3 mol / L.

[0055] Preferably, the drying conditions in step (4) are 100-150° C. for 1-4 h; and the calcination conditions are 500-700° C. for 2-6 h.

[0056] The present invention will be described in detail below through examples.

[0057] In the following examples and comparative examples, the infrared acid content of pyridine and n-butylpyridine was determined by pyridine and n-butylpyridine adsorption infrared spectroscopy, using a Nicolet 6700 Fourier transform infrared spectrometer from NICOLET, USA, and the process is as follows:

[0058] Take 20 mg of the ground sample (with a particle size less than 200 mesh) and press it into a thin sheet with a diameter of 20 mm. Put it on the sample holder of the absorption cell. Take 200 mg of the sample (sheet) and put it into the hanging cup at the lower end of the quartz spring (record the spring length, x1, mm, before adding the sample). Connect the absorption cell and the adsorption tube, start evacuation and purification. When the vacuum reaches 4×10-2Pa, heat it to 500℃ and keep it for 1h to remove the surface adsorbent of the sample (at this time, record it as the spring length after sample purification, x2, mm). Then cool it to room temperature, adsorb pyridine (n-butylpyridine) to saturation, then heat it to 160℃, balance it for 1 hour, desorb the physically adsorbed pyridine (at this time, record it as the spring length after pyridine adsorption, x3, mm), and use the pyridine (n-butylpyridine) weight adsorption method to obtain the total acid content.

[0059] The surface area and pore volume were determined by using the low-temperature nitrogen adsorption method (BET method);

[0060] The Na2O content in the molecular sieve and the SiO2 / Al2O3 molar ratio of the molecular sieve were determined by fluorescence method;

[0061] The unit cell parameters and relative crystallinity of the molecular sieve were determined by XRD method, the instrument was Rigaku Dmax-2500 X-ray diffractometer, using Cukα radiation, graphite single crystal filtering, operating tube voltage 35KV, tube current 40mA, scanning speed (2θ) 2° / min, scanning range 4°~35°. The standard sample was the Y-type molecular sieve raw powder used in Example 1 of the present invention.

[0062] Example 1

[0063] Molecular sieve modification process:

[0064] (1) Take the raw powder of NaY molecular sieve prepared in the laboratory, mix it with ammonium nitrate with a concentration of 0.5 mol / L at a liquid-solid ratio of 3:1, exchange it at 70°C for 3 hours, and repeat this process 3 times. The Na content in the Y molecular sieve after exchange is 2.5% in terms of Na2O;

[0065] (2) hydrothermally treating the Y molecular sieve obtained in step (1) at 550°C and 0.1 MPa for 2 hours; repeating this process once;

[0066] (3) The molecular sieve obtained in step (2) was stirred and mixed with distilled water at a liquid-to-solid ratio of 5:1, and then the temperature was raised to 80°C. During the stirring process, 400 ml of 0.5 mol / L aluminum sulfate solution was added, and the mixture was reacted at a constant temperature for 2 hours;

[0067] (4) adding the aluminum salt-treated Y molecular sieve obtained in step (3) into a 2 mol / L NaNO3 aqueous solution and treating at 60°C for 2 h;

[0068] (5) The Y molecular sieve treated with NaNO3 in step (4) was added to a 0.3 mol / L sodium naphthalenesulfonate aqueous solution and stirred at room temperature for 3 h;

[0069] (6) The molecular sieve treated with sodium naphthalenesulfonate in step (5) was mixed with ammonium nitrate having a concentration of 2.0 mol / L at a liquid-to-solid ratio of 3:1, exchanged at 80°C for 1 hour, and this process was repeated 3 times. The molecular sieve was then dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain the modified Y molecular sieve of Example 1, numbered Y-1.

[0070] Example 2

[0071] (1) Take the raw powder of NaY molecular sieve prepared in the laboratory, mix it with ammonium nitrate with a concentration of 2.0 mol / L at a liquid-to-solid ratio of 3:1, exchange it at 80°C for 2 h, and repeat this process once. The Na content in the Y molecular sieve after exchange is 2.7% in terms of Na2O.

[0072] (2) The Y molecular sieve obtained in step (1) was hydrothermally treated at 580°C and 0.1 MPa for 2 h, and this process was repeated once.

[0073] (3) The molecular sieve obtained in step (2) was treated with a 0.4 mol / L ammonium fluorosilicate solution at a liquid-to-solid ratio of 5:1 at 90°C for 2 h;

[0074] (4) adding the ammonium fluorosilicate treated Y molecular sieve obtained in step (3) into a 0.8 mol / L Na(NO3) aqueous solution and treating at 70°C for 2 h;

[0075] (5) The Y molecular sieve treated with NaNO3 in step (4) was added to a 0.5 mol / L aqueous solution of potassium naphthalenesulfonate and stirred at room temperature for 3 h;

[0076] (6) The molecular sieve treated with sodium naphthalenesulfonate in step (5) was mixed with ammonium nitrate having a concentration of 1.5 mol / L at a liquid-to-solid ratio of 3:1, exchanged at 60°C for 2 hours, and this process was repeated twice. The molecular sieve was then dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain the modified Y molecular sieve of Example 2, numbered Y-2.

[0077] Example 3

[0078] (1) Take the raw powder of NaY molecular sieve prepared in the laboratory, mix it with ammonium nitrate with a concentration of 2.0 mol / L at a liquid-to-solid ratio of 3:1, exchange it at 80°C for 2 hours, and repeat this process twice. The Na content in the Y molecular sieve after exchange is 2.3% in terms of Na2O;

[0079] (2) The Y molecular sieve obtained in step (1) was hydrothermally treated at 630°C and 0.1 MPa for 2 hours.

[0080] (3) The molecular sieve obtained in step (2) was mixed with a 0.6 mol / L dilute nitric acid solution at a liquid-to-solid ratio of 5:1, and then the temperature was raised to 95° C. and the reaction was carried out at a constant temperature for 2 hours.

[0081] (4) adding the Y molecular sieve treated with dilute nitric acid obtained in step (3) into a 1.5 mol / L Na(NO3) aqueous solution and treating at 70°C for 2 h;

[0082] (5) The Y molecular sieve treated with Na(NO3) in step (4) was added to a 0.5 mol / L aqueous solution of potassium naphthalenesulfonate and stirred at room temperature for 2 h;

[0083] (6) The molecular sieve treated with potassium naphthalenesulfonate in step (5) was mixed with ammonium nitrate having a concentration of 1.5 mol / L at a liquid-to-solid ratio of 3:1, exchanged at 80°C for 3 hours, and this process was repeated twice. The molecular sieve was then dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain the modified Y molecular sieve of Example 3, numbered Y-3.

[0084] Example 4

[0085] (1) Take the raw powder of NaY molecular sieve prepared in the laboratory, mix it with ammonium nitrate with a concentration of 0.5 mol / L at a liquid-solid ratio of 3:1, exchange it at 70°C for 3 hours, and repeat this process 3 times. The Na content in the Y molecular sieve after exchange is 2.5% in terms of Na2O;

[0086] (2) The Y molecular sieve obtained in step (1) was treated with 0.2 mol / L ammonium fluorosilicate solution at a liquid-to-solid ratio of 6:1 and treated at 80°C for 2 h;

[0087] (3) The Y molecular sieve obtained in step (2) was hydrothermally treated at 0.2 MPa and 520°C for 2 h, and this process was repeated once;

[0088] (4) The molecular sieve obtained in step (3) was stirred and mixed with 0.6 mol / L aluminum sulfate solution at a liquid-to-solid ratio of 5:1, and then the temperature was raised to 75° C. and the reaction was carried out at a constant temperature for 2 hours.

[0089] (5) adding the aluminum salt-treated Y molecular sieve obtained in step (4) into a 0.6 mol / L Na(NO3) aqueous solution and treating at 50°C for 2 h;

[0090] (6) adding the Y molecular sieve treated with Na(NO3) in step (5) into a 0.3 mol / L aqueous solution of potassium naphthalenesulfonate and stirring at room temperature for 4 h;

[0091] (7) The molecular sieve treated with potassium naphthalenesulfonate in step (6) was mixed with ammonium nitrate having a concentration of 2.0 mol / L at a liquid-to-solid ratio of 3:1, exchanged at 80°C for 2 hours, and this process was repeated twice. The molecular sieve was then dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain the modified Y molecular sieve of Example 4, numbered Y-4.

[0092] Example 5

[0093] (1) Take the raw powder of NaY molecular sieve prepared in the laboratory, mix it with ammonium nitrate with a concentration of 1.5 mol / L at a liquid-to-solid ratio of 3:1, exchange it at 80°C for 3 hours, and repeat this process once. The Na content in the Y molecular sieve after exchange is 2.9% in terms of Na2O;

[0094] (2) The Y molecular sieve obtained in step (1) was treated with 0.2 mol / L ammonium fluorosilicate solution at a liquid-to-solid ratio of 6:1 and treated at 80°C for 2 h;

[0095] (3) The Y molecular sieve obtained in step (2) was hydrothermally treated at 0.1 MPa and 550°C for 3 h, and this process was repeated once;

[0096] (4) The molecular sieve obtained in step (3) was stirred and mixed with 0.6 mol / L aluminum sulfate solution at a liquid-to-solid ratio of 5:1, and then the temperature was raised to 75° C. and the reaction was carried out at a constant temperature for 2 hours.

[0097] (5) adding the aluminum salt-treated Y molecular sieve obtained in step (4) into a 0.5 mol / L Na(NO3) aqueous solution and treating at 50°C for 2.5 h;

[0098] (6) adding the Y molecular sieve treated with Na(NO3) in step (5) into a 0.4 mol / L sodium naphthalenesulfonate aqueous solution and stirring at room temperature for 4 h;

[0099] (7) The molecular sieve treated with potassium naphthalenesulfonate in step (6) was mixed with ammonium nitrate having a concentration of 2.0 mol / L at a liquid-to-solid ratio of 3:1, exchanged at 80°C for 2 hours, and this process was repeated twice. The molecular sieve was then dried at 120°C for 4 hours and calcined at 550°C for 4 hours to obtain the modified Y molecular sieve of Example 5, which was numbered Y-5.

[0100] Comparative Example 1

[0101] (1) Take the raw powder of NaY molecular sieve prepared in the laboratory, mix it with ammonium nitrate with a concentration of 0.5 mol / L at a liquid-solid ratio of 3:1, exchange it at 70°C for 3 hours, and repeat this process 3 times. The Na content in the Y molecular sieve after exchange is 2.5% in terms of Na2O;

[0102] (2) The Y molecular sieve obtained in step (1) was hydrothermally treated at 550°C and 0.1 MPa for 2 hours; this process was repeated once.

[0103] (3) The molecular sieve obtained in step (2) was mixed with 0.5 mol / L aluminum sulfate solution at a liquid-to-solid ratio of 5:1, and reacted at 80°C for 2 hours.

[0104] The molecular sieve treated with aluminum salt in step (3) was dried at 120° C. for 4 h and calcined at 550° C. for 4 h to obtain the modified Y molecular sieve of Comparative Example 1, which was numbered B-1.

[0105] Comparative Example 2

[0106] (1) Take 200g of NaY molecular sieve powder prepared in the laboratory, mix it with ammonium nitrate with a concentration of 0.5mol / L at a liquid-to-solid ratio of 3:1, exchange it at 70℃ for 3 hours, and repeat this process 3 times. The Na content in the Y molecular sieve after exchange is 2.5% in terms of Na2O;

[0107] (2) The Y molecular sieve obtained in step (1) was treated with 0.2 mol / L ammonium fluorosilicate solution at a liquid-to-solid ratio of 6:1 and treated at 80°C for 2 h;

[0108] (3) The Y molecular sieve obtained in step (2) was hydrothermally treated at 0.2 MPa and 520°C for 2 h, and this process was repeated once;

[0109] (4) The molecular sieve obtained in step (3) was mixed with 0.6 mol / L aluminum sulfate solution at a liquid-to-solid ratio of 5:1 and reacted at 75°C for 2 hours. After drying at 120°C for 4 hours and calcining at 550°C for 4 hours, the modified Y molecular sieve of Comparative Example 2 was obtained, which was numbered B-2.

[0110] The properties of the molecular sieves prepared in the above examples and comparative examples are shown in Table 1.

[0111] Table 1 Comparison of the physicochemical properties of the molecular sieves of the embodiment and the comparative example

[0112]

Claims

1. A modified Y-type molecular sieve, characterized in that: Based on the total amount of the modified Y-type molecular sieve, the Y-type molecular sieve contains 2.0-6.0wt% of Na2O by mass; the ratio of the pyridine infrared acid content to the butylpyridine infrared acid content of the Y-type molecular sieve is 5-60; and the pyridine infrared acid content is 0.05-0.6mmol / g.

2. The modified Y-type molecular sieve according to claim 1, characterized in that: The modified Y-type molecular sieve has a specific surface area of ​​600 to 900 m 2 / g; pore volume 0.30~0.60ml / g; relative crystallinity 60%~140%, unit cell parameter 2.430~2.450; silicon-aluminum molar ratio 5~50:

1.

3. A method for preparing the modified Y-type molecular sieve according to claim 1, characterized in that: The steps include: (1) pretreating the NaY molecular sieve to obtain a de-sodiumated and de-aluminized Y-type molecular sieve; (2) treating the pretreated Y molecular sieve obtained in step (1) with an aqueous solution of NaNO3; (3) adding the Y molecular sieve treated with the NaNO3 aqueous solution in step (2) to a naphthalenesulfonate aqueous solution for immersion treatment; (4) The treated molecular sieve in step (3) is subjected to an ion exchange reaction with ammonium salt, and then dried and calcined to obtain a modified Y molecular sieve.

4. The method according to claim 3, characterized in that: The pretreatment process in step (1) includes one or a combination of ammonium ion exchange, hydrothermal dealumination, aluminum salt dealumination, fluorosilicate dealumination and acid dealumination.

5. The method according to claim 4, characterized in that: The pretreatment process in step (1) includes: (a) subjecting a NaY molecular sieve to an ammonium ion exchange reaction with an ammonium salt aqueous solution to obtain a sodium-free Y-type molecular sieve; (b) subjecting the de-sodiumized Y-type molecular sieve to hydrothermal dealumination to obtain a hydrothermal dealumination product; (c) subjecting the hydrothermal dealumination product to chemical dealumination to obtain the desodium-dealuminized Y-type molecular sieve, wherein the chemical dealumination is aluminum salt dealumination, fluorosilicate dealumination or acid dealumination.

6. The method according to claim 5, characterized in that: The process of the ammonium salt ion exchange reaction in step (a) is: exchanging the NaY molecular sieve with an ammonium salt aqueous solution at 60-120° C. for 1-3 hours, with the number of exchanges being 1-4 times, to obtain the desodiumated Y-type molecular sieve.

7. The method according to claim 5, characterized in that: The hydrothermal dealumination process in step (b) is as follows: the desodiumated Y-type molecular sieve is contacted with water vapor at a temperature of 520-700° C. and a pressure of 0.01-0.5 MPa for 1-6 hours.

8. The method according to claim 5, characterized in that: The process of chemical dealumination in step (c) is as follows: the product of hydrothermal dealumination is subjected to a constant temperature reaction with an aluminum salt solution, an ammonium fluorosilicate solution or a nitric acid solution at a temperature of 50-120° C. for 0.5-3 h.

9. The method according to claim 3, characterized in that: The NaNO3 aqueous solution treatment process described in step (2) is to add the Y molecular sieve treated with aluminum salt in step (3) into a NaNO3 aqueous solution with a concentration of 0.1 to 3.0 wt%, and heat it to 40 to 80° C. for constant temperature reaction for 1 to 4 hours.

10. The method according to claim 3, characterized in that: The naphthalenesulfonate used in the naphthalenesulfonate treatment process of step (3) is sodium naphthalenesulfonate or potassium naphthalenesulfonate, and the naphthalenesulfonate in the solution is 0.2-1 mol / L in terms of K or Na ion concentration, and the treatment condition is stirring treatment at room temperature for 2-6 hours.

11. The method according to claim 3, characterized in that: The ammonium salt ion exchange reaction step described in step (4) is to exchange the molecular sieve obtained in step (3) with an ammonium salt aqueous solution at 60-120° C. for 1-3 hours, and the number of exchanges is 1-4 times.

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